Detecting Windows 10 Dark/Light mode

MainWindow.xaml

<Window x:Class="WpfApp1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp1"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>

      <TextBlock HorizontalAlignment="Center" VerticalAlignment="Center" x:Name="theTextBlock" />
        
    </Grid>
</Window>

MainWindow.xaml.cs

using System;
using System.Windows;
using System.Windows.Interop;

namespace WpfApp1
{
  public partial class MainWindow : Window
  {
    private bool isLightMode = false;

    public MainWindow()
    {
      InitializeComponent();

      isLightMode = IsLightMode();
      theTextBlock.Text = $"Current Mode: {(isLightMode ? "Light" : "Dark")}";
      this.SourceInitialized += MainWindow_SourceInitialized;
    }

    private IntPtr hwnd;
    private HwndSource hsource;

    private void MainWindow_SourceInitialized(object sender, EventArgs e)
    {
      if ((hwnd = new WindowInteropHelper(this).Handle) == IntPtr.Zero)
      {
        throw new InvalidOperationException("Could not get window handle.");
      }

      hsource = HwndSource.FromHwnd(hwnd);
      hsource?.AddHook(WndProc);
    }

    private const int WM_WININICHANGE = 0x001A;

    private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
    {
      switch (msg)
      {
        case WM_WININICHANGE:

          // Respond to dark/light theme change

          var newMode = IsLightMode();
          if (newMode != isLightMode)
          {
            isLightMode = newMode;
            theTextBlock.Text = $"Current Mode: {(isLightMode ? "Light" : "Dark")}";
          }

          return IntPtr.Zero;

        default:
          return IntPtr.Zero;
      }
    }

    private bool IsLightMode()
    {
      var is_light_mode = true;
      try
      {
        var v = Microsoft.Win32.Registry.GetValue(
          @"HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Themes\Personalize", "AppsUseLightTheme", "1");
        if (v != null && v.ToString() == "0")
        {
          is_light_mode = false;
        }
      }
      catch
      {
        // ignored
      }

      return is_light_mode;
    }
  }
}